1. Field of the Invention
This invention relates generally to elevator security systems, and more particularly, to elevator security systems employing a voice-recognition device to control access to the elevator car.
2. Description of the Prior Art
Although the chief responsibility of the elevator attendant in older elevator systems was to operate the elevator car, the elevator attendant also provided a degree of security by limiting access to authorized, or at least familiar, passengers. With the advent of the user-operated elevator system, and the demise of the elevator attendant, it has become necessary to provide an elevator security system to insure that only authorized personnel have access to the elevator car. Access control is critical in high-rise office buildings and especially in living units where the elevator system must operate twenty-four hours a day. It is impossible for building security personnel to effectively monitor elevator usage and prohibit unauthorized users from gaining access to an elevator car with today's widespread use of multi-car elevator systems. Obviously, the problem of unauthorized usage is especially critical in landings above the main landing where security personnel are not routinely stationed.
For comprehensive protection, an elevator security system must control use of the elevator car in two different situations. First, the security system must detect a hall call initiated by an unauthorized user at any landing. The elevator system should not respond to such calls thereby preventing the unauthorized user from gaining access to an elevator car. Second, once an authorized user has entered an elevator car and initiated a car call to the desired landing, by actuating the proper switch, the security system must insure that the authorized user is permitted access to the landing selected. If the authorized user is prohibited access to the selected landing the car call should be disregarded. Furthermore, the security system should be designed such that unauthorized users do not gain access to an elevator car or landing by simply observing an authorized user entering a code or by obtaining the code through other deceptive means.
One prior art security system is disclosed in U.S. Pat. No. 3,388,376 wherein a car call is initiated by operation of a set of security call buttons in a coded sequence. Note that with this system an unauthorized passenger can gain access to a landing by learning a coded sequence for that landing, for instance, by simply observing an authorized user entering the code. Also, this prior art technique does not provide the first security function previously described, i.e., detecting and disregarding hall calls initiated by unauthorized users.
Another security system in widespread use today, especially in automatic banking machines, involves entering two code words or numbers. The first code, entered by keyboard or card reader, is simply an identifying code, e.g., a social security number or an account number. The second code known only to the user is then entered. If the identifying code and the secret code designate the same user, a positive identification is made. Such a security system, exemplified by U.S. Pat. No. 4,198,619, could be incorporated into an elevator system. Since this security system requires entry of two code words, it is less susceptible to false or incorrect identification as the prior art security system discussed above. It can, nevertheless, be circumvented by theft of a card when the thief knows or can learn the owner's secret code. Also note that both of these prior art security systems require the user to remember at least one code to operate the elevator system. Additional codes may have to be remembered for gaining access to specific landings served by the elevator system.
The present invention overcomes these disadvantages by providing access to an elevator system by analyzing the user's voice signal and comparing the results with the voice signals of all authorized users stored in memory. These and other advantages of the present invention are discussed below in the description of the preferred embodiments.